Hi Skyrider! I didn't have mine in a cone, but if you do use one, his head should be sticking out the bottom enough to stick, cut, and behead. The spot I was aiming at was the upper rear of the skull, but looking the pics and comments posted by Half-a-dozen,
https://www.backyardchickens.com/forum/viewtopic.php?id=90607
I'm thinking I should've aimed straight into the beak into a spot lower on the back of the head. Maybe that's why mine didn't go as quietly into the good night as I'd hoped.
I had mine hung upside down with a loop around the feet, and after the brain stick, I pulled the head down to pull the skin taut, and made long deep cuts
just under (actually
over, as the bird was upside down) the earlobes on both sides. There's a deep groove in the roof of the bird's mouth, that's what the knife goes into for the brain stick. Once the bleeding slowed, I went ahead and took the head off, I kept the head pulled down tight, and sliced across the throat, then twisted to separate the neck bones, and cut through the last bit of skin holding it on.
I was running out of daylight, and just wanted to get all three dispatched while I could still see well enough not to cut my thumb off or something equally unpleasant. They weren't easy to pluck, so I knew I hadn't quite gotten it right. I had to dunk them in hot water repeatedly, it took forever to get them plucked. The rest of the cleaning was pretty quick. I really want a tub-style plucker!
I have 3 more to process, but I'm giving them a couple of weeks longer to fatten up, first.
When I did the brain stick, I went straight in through the beak, aimed up just a little, then gave the knife a bit of a twist. Next time I'll aim straight at the back of the skull through the beak, and twist. I hope that works better.